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YC S21 companies (Summer 2021)

All 390 companies in Y Combinator's Summer 2021 batch, with team size, growth, open roles and funding.

Updated weekly, last on November 9, 2026. Roster from Y Combinator's public directory.

Hiring the mostlast 60 days
36 roles
StepfulS21
  1. 2Exa28
  2. 3ARQ24
See all 50
Fastest growingteam, 6 months
+100%
HireboltS21
  1. 2Aqua+93%
  2. 3Confido+89%
See all 100
Shrinkingteam, 12 months
−66%
SecodaS21
  1. 2Portão 3−57%
  2. 3Affogato AI−50%
See all 43
Raised the mostlast 12 months
$250M
ExaS21
  1. 2Slash$100M
  2. 3Turion Space$75M
See all 30
Companies
390
Active
284
Hiring, last 60 days
50
Open roles, 60 days
274
People on these teams
16,749
Showing 50 of 390 companies
CompanyTeam6 mo12 moOpen rolesTotal raisedLast round
The everything app for LATAM
1,132+10%+27%1$71MSeries A$47M, Jun 2022
A modern-day mental healthcare company for global workforces.
693−2%+1%0$32.8MCorporate round$19.8M, Mar 2023
Learning platform for job seekers with job applications automation
533−5%−5%0$9.5MSeries A$8M, Mar 2023
Fair, simple and accessible financial services
480+4%+15%2$86.8MCorporate round$53M, May 2026
Online Training for Healthcare Jobs
449+12%+33%36$111MSeries C$55M, Jun 2026
Onebrief makes military headquarters run seamlessly
391+9%+55%7$311MGrant$114K, Jul 2026
Account Receivables Platform for Latin American Enterprises
367+10%+27%14$66.5MSeries A$48M, Apr 2025
IP operating software for brands and content companies
289+6%+19%0$89MSeries B$48M, Sep 2025
The global financial platform for affluent consumers in the Americas.
277+49%+147%24
Online cohort based courses for architects, engineers and designers…
261−7%−16%0$1.2MSeed$1.2M, May 2023
Web search rebuilt for LLMs
243+46%+117%28$357MSeries C$250M, May 2026
B2B payments, transforming Africa's cash economy
240+2%+2%YC$18.2MNon-equity support$15M, Nov 2024
We help students in Latin America graduate from College.
226−5%+1%0$460KYC investment$125K, Aug 2021
Payments and scheduling for services professionals in LATAM
186+13%+28%0$1.6MSeed$1.5M, Nov 2021
Transforming Mental Health for Corporate Asia
170+2%+33%YC$2.9MSeed$2M, Feb 2022
One API to get clean data from any website for your AI agents at scale
160+13%+27%0$2MSeed$2M, Dec 2021
Learning app for school students in Southeast Asia
157+13%+15%0$1.7MSeed$1.6M, Jan 2022
We make instant offers to buy homes in India
142+7%+37%0$7.2MSeed$5.8M, Jun 2022
Track & Boost Your Brand’s Visibility in AI Search
141+3%+22%1$2.6MSeed$2.5M, Sep 2021
Offers insurance to customers in a convenient & transparent way
136+5%+15%0$6.7MSeed$3.3M, Nov 2024
Get matched with top 1% of talents in 24h
134−10%−11%1$2.9MNon-equity support$800K, Mar 2022
Turning space into a transportation layer for Earth
131+20%+30%3$54.3MSeries A$44M, Nov 2024
AppX helps social media creators launch their own mobile apps.
129+2%+30%2$1.4MSeed$1.3M, Jan 2022
Corporate Card solution for Indian businesses
127−8%−9%0$38.3MDebt$7.1M, May 2022
Amazon Level Logistics for eCommerce Companies in MENA.
126+11%+8%0$2.6MPre-seed$2.4M, Oct 2021
We visually monitor space objects for governments and defense
125+12%+21%0$38.4MSeries B$26.4M, Sep 2026
AI-enabled financial automation and intelligence for CPG Brands
121+89%+163%22$75MSeries B$55M, Sep 2026
One source of truth for financial data.
107+18%+45%1$46.1MSeries B$29.2M, Sep 2025
Lattice for Latam with personalized learning and development
107+2%+1%0$300KSeed$300K, Oct 2024
Building the human layer of AI
104+4%+33%8$64.2MSeries B$40M, Nov 2025
Water risk mitigation for industrial sites
102 −1%0$18.3MNon-equity support$150K, Sep 2026
Building India's fast food empire
101 −2%0
Global online sales platform
101−5%+7%3$125KYC investment$125K, Jan 2022
Easiest way for companies to process data requests from governments
99+22%+62%5$41.2MSeries A$21.2M, Sep 2025
Banking, corporate cards, stablecoin payments, available globally.
98+31%+63%3$160MSeries C$100M, Apr 2026
Simplified digital health insurance for Filipino SMBs
98+4%+11%12$6.5MSeed$6.5M, Jul 2024
Building Job driven Virtual Tech University for India 🇮🇳
95−7%+32%YC$125KYC investment$125K, Jan 2022
AI-native on-call and incident response carefully crafted to help…
93+22%+27%1$15.2MSeries A$12M, Aug 2023
Making it easy for employees to donate and volunteer with good causes.
93−8%−13%0$12.8MSeries A$10M, Dec 2021
Organic and gourmet high-protein meals, designed for longevity.
91+8%+7%0$16.1MSeed$14M, May 2022
Cohort-based online courses for professionals in Latin America
90+3%+2%0$2.4MSeed$2.3M, Mar 2022
Gusto for India
88−3%−8%1$4.1MSeed$4M, Sep 2021
Flexible On-Demand Storage Space for Household, SMEs & Travellers.
85+12%+20%0$630KSeed$505K, Dec 2021
The AI Native Billing Platform
84−7%+6%YC$22.1MSeries A$15M, Mar 2024
A mobile app. It allows employees to get paid their salary on-demand.
84+5%−1%1$64MUndisclosed round$21.7M, Jun 2025
App to help people quit or cut back on alcohol use
83+1%+2%YC$27.4MUndisclosed round$10M, Apr 2022
We help Accountants automate work and serve their customers online
83+9%+9%1$2.7MSeed$2.2M, Mar 2022
The most magical personal Voice-Led AI English Learning Buddy for Kids
82+4%+9%0$125KYC investment$125K, Mar 2022
Financial data your AI can actually trust
82+1%−1%0$3MSeed$1M, Aug 2021
We make software for bookkeepers.
81−2%−9%1$15.1MSeries A$6.5M, Dec 2025

How this works

1. The roster

Every launched company in YC's public directory, with its batch, status, industry and location. New companies show up the week YC lists them.

2. The numbers

Each company is matched to Crustdata by its website. Crustdata adds team size and its change over 6 and 12 months, open roles from job postings, reported funding, and founders' past employers.

3. The lists

Hiring the most counts distinct roles posted in the last 60 days. Growth needs 10+ people today, shrinking 20+ a year ago, so tiny teams do not top the lists. Rebuilt every week.

Built with Crustdata. Get your own API key and build your own.

The numbers on this page come from three Crustdata API calls. Crustdata tags 5,000+ companies with Y Combinator as an investor; swap the filter for any investor, industry or headcount range and track your own list, with founders' work emails one call away.

  • Company search for team size, growth and funding
  • Job search with a count by company, for who is hiring and for what
  • A watch that re-runs the search weekly and sends only what changed
# 1. every company with Y Combinator as an investor
curl https://api.crustdata.com/company/search \
  -H "authorization: Bearer $CRUSTDATA_API_KEY" \
  -H "x-api-version: 2025-11-01" \
  -d '{
    "filters": { "field": "funding.investors",
                 "type": "in", "value": ["Y Combinator"] },
    "fields": ["basic_info.name",
      "headcount.total", "headcount.growth_percent",
      "funding.total_investment_usd"],
    "limit": 100
  }'

# 2. open listings per company, last 60 days (limit 0 = counts only)
curl https://api.crustdata.com/job/search \
  -H "authorization: Bearer $CRUSTDATA_API_KEY" \
  -H "x-api-version: 2025-11-01" \
  -d '{
  "filters": { "op": "and", "conditions": [
    { "field": "company.basic_info.company_id",
      "type": "in", "value": [...] },
    { "field": "metadata.date_added",
      "type": "=>", "value": "2026-08-24" } ]},
  "limit": 0,
  "aggregations": [{ "type": "group_by",
    "field": "company.basic_info.company_id", "agg": "count" }]
}'

# 3. the same company filter as a weekly watch: POST /watch/company/search

Questions about YC S21 companies

How many YC S21 companies are there?

390 companies were in Y Combinator's Summer 2021 batch (S21); 284 are active.

Which YC S21 companies are hiring?

50 companies posted roles in the last 60 days, led by Stepful (36 roles), Exa (28 roles) and ARQ (24 roles). 85 mark themselves as hiring on YC's directory.

Which YC S21 companies are growing fastest?

By team growth over 6 months (10+ people): Hirebolt (+100%), Aqua (+93%) and Confido (+89%).

Which YC S21 companies raised the most?

Largest latest rounds in the last 12 months, after their YC batch: Exa ($250M), Slash ($100M) and Turion Space ($75M).

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